The present invention relates to a system for the assembly of structural panel systems, and particularly to the assembly of light-transmitting sections such as windows, skylights and roof glazing of buildings.
While the traditional glazing bar assembly system for light transmitting portions of buildings works fairly well for supporting glass, its disadvantages are numerous and weighty when used with transparent structural panels of other materials. For example, such structural panels may be formed as thin parallel sheets of plastic interconnected by parallel ribs which give stiffness and thermal insulation qualities to such panels. Such plastic panels are more flexible and lighter in weight than glass, but also have much larger thermal coefficients of expansion than glass. These characteristics help to make previous structures, incorporating such plastic panels held between rubber or rubber-like gaskets, supported in metal frames liable to leakage, to gasket pull-out, and to panel blow-out due to air pressure differences. Excessive noise is caused by movement of such plastic panels against gasket material in response to the extreme difference between the thermal coefficients of expansion of the dissimilar materials and because of the grasping action of the conventional gasketing materials on panel surfaces. Standard structural plastic sheet is not recommended to be used beyond a certain length without a mullion because of the possibility of being dislocated by negative air pressure differences from wind passing over the panel.
The traditional assembly system for roof-surface portions, especially light transmitting portions, requires a solid structural frame system for support. Its disadvantages are numerous, especially in the spanning of very long distances, which requires large and very expensive structural systems. This is especially true in curved applications where the structural system must be preshaped in a factory and shipped in curved shape to the job site.
It is one of the objects of the present invention to overcome these and other disadvantages and drawbacks of the prior art glazing bar systems for incorporation of plastic panels in structures and to provide a system which is simple, reliable, and relatively easily used in the field.
It is another object of the invention to provide a structural system by which the plastic panel units according to the invention can be custom cut at a construction site and then joined edge-to-edge to form a "skin" of a desired width and length.
It is another of the objects of the present invention to provide a weathertight structural system which is extremely light in weight, amply strong in tension and relatively inexpensive.
It is another of the objects of the present invention to provide a structural system that may be shipped flat to the job site and assume the desired curved shape during assembly.
Another object of the present invention is to provide a structure utilizing plastic sheets or panels and of such a design that it can extend between relatively widely-spaced supporting structures.
The present invention achieves these objects by providing a glazing bar system incorporating a novel structural fastening arrangement for holding plastic panels in place. The system according to the present invention is a clamping bar glazing system comprising panel units having at least one retaining member such as a retainer strip of plastic material located along one margin of a face of a panel unit, and having two glazing bars, at least one including a flange to engage the retainer strip, with one glazing bar on each side of the panel, with the flange engaging the retainer strip to hold the panel between the glazing bars.
In a preferred embodiment of the invention a retainer strip of plastic material is provided, protruding outward along the margin of a panel on each of the opposite sides. The glazing bars are extrusions which have flanges extending toward the sheet-like panel. When the resulting panel is engaged on both sides by the glazing bars, it is locked into its desired location by the flanges.
It is a feature of the panel unit according to the invention that, using an abrasion-resistant, low-friction surface on the outer side of the projecting retainer strip, it is possible to avoid the noise created by the movement of the panel against a surface of different properties, resulting from differences of expansion and contraction.
It is another feature of the structural arrangement according to the present invention that the retainer strip extending along the margin of the panel is a natural dam against water leakage past the juncture of the panel and the supporting glazing bar combination.
It is a further feature of one embodiment of the invention that it includes a chamber within the glazing bar assembly where cables or other structural members may be located, to support the assembly as a "skin" stretched between retaining walls or other structural supports.
It is a further feature of one embodiment of the invention that the assembly acting as a "skin" can be suspended from a cable web structural system by attaching suitable cables to the glazing bar assemblies.
The present invention also provides structures for use in interconnecting two frame and panel assemblies perpendicular to each other to create a roof and removable wall system.
The foregoing and other objectives, features, and advantages of the invention will be more readily understood upon consideration of the following detailed description of the invention, taken in conjunction with the accompanying drawings.